Sheets or blankets of such materials as paper, fiber glass, polyethylene, etc. are frequently manufactured continuously and are accumulated at the end of a process line into rolls by a winder. Usually, it is desired that the rolls be as compact as the tear strength of the material being wound will allow to conserve space in handling, storing, and shipping the rolled goods. It is also desirable, and usually essential, that the ends of the rolled goods be square.
To achieve the desired results, a winder must synchronize its linear take-up speed, regardless of the diameter of the rolled goods at the time, with the incoming speed of the sheet or blanket material from the process line. Failure to quickly compensate for changes in speed on the process line will either result in excess slack in the material being wound, usually causing telescoping of the roll, or will alternatively so stress or stretch the material to cause it to tear, disrupting the winding process and creating scrap material. The winder must not only be able to rapidly compensate for changes in speed during continuous operation, but also during startup and shutdown of the process.
Another requirement of the winder is that it permit rapid removal of finished roll goods from the winder and rapid initiation of a new roll to avoid slowing down or stopping the process line.
Still another requirement for the winder is that it apply a uniform and proper amount of tension to the sheet or blanket being rolled, particularly when the sheet or blanket is compressible and/or has low tear resistance. It is desirable that the amount of tension can be varied to permit the winder to wind different types of material having a wide range of tensile strengths or tear resistances.
It is also desirable that the winder be capable of compensating for variations in alignment of the sheet or blanket or for variations in the angle at which the sheet or blanket approaches the winder.
Finally, it is desirable that the winder be capable of applying only a desired amount of compression or load onto the roll of goods as it is being wound regardless of the density of the material being wound or the size of the roll at any point during the forming of the roll.
Finally, it is desired that the winder be able to compensate for misalignment or changes in alignment of the incoming sheet or blanket with respect to the winder and/or the partial roll of goods being wound. While prior art winders achieved some of these desirable features sufficient of the features were not obtained in sufficient degree to always permit square end roll packages to be achieved, particularly when winding sheet or blankets having very low tear strengths.